Reflectance Spectrophotometry Research Articles

Local carbachol application induces oral microvascular recruitment and improves gastric tissue oxygenation during hemorrhagic shock in dogs.

Hemorrhagic shock is characterized by derangements of the gastrointestinal microcirculation. Topical therapy with nitroglycerine or iloprost improves gastric tissue oxygenation but not regional perfusion, probably due to precapillary adrenergic innervation. Therefore, this study was designed to investigate the local effect of the parasympathomimetic carbachol alone and in combination with either nitroglycerine or iloprost on gastric and oral microcirculation during hemorrhagic shock. In a cross-over design five female foxhounds were repeatedly randomized into six experimental groups. Carbachol, or carbachol in combination with either nitroglycerine or iloprost were applied topically to the oral and gastric mucosa. Saline, nitroglycerine, or iloprost application alone served as control groups. Then, a fixed-volume hemorrhage was induced by arterial blood withdrawal followed by blood retransfusion after 1h of shock. Gastric and oral microcirculation was determined using reflectance spectrophotometry and laser Doppler flowmetry. Oral microcirculation was visualized with videomicroscopy. Statistics: 2-way-ANOVA for repeated measurements and Bonferroni post-hoc analysis (mean ± SEM; p < 0.05). The induction of hemorrhage led to a decrease of gastric and oral tissue oxygenation, that was ameliorated by local carbachol and nitroglycerine application at the gastric mucosa. The sole use of local iloprost did not improve gastric tissue oxygenation but could be supplemented by local carbachol treatment. Adding carbachol to nitroglycerine did not further increase gastric tissue oxygenation. Gastric microvascular blood flow remained unchanged in all experimental groups. Oral microvascular blood flow, microvascular flow index and total vessel density decreased during shock. Local carbachol supply improved oral vessel density during shock and oral microvascular flow index in the late course of hemorrhage. The specific effect of shifting the autonomous balance by local carbachol treatment on microcirculatory variables varies between parts of the gastrointestinal tract. Contrary to our expectations, the improvement of gastric tissue oxygenation by local carbachol or nitroglycerine application was not related to increased microvascular perfusion. When carbachol is used in combination with local vasodilators, the additional effect on gastric tissue oxygenation depends on the specific drug combination. Therefore, modulation of tissue oxygen consumption, mitochondrial function or alterations in regional blood flow distribution should be investigated.

Geographic origin classification and simultaneous determination of methylxanthines in vietnamese tea using chemometrics based on the near infrared reflectance spectroscopy

This paper reported the results of classification of geographic origin and simultaneous analysis of three methylxanthines (caffeine, theobromine, theophylline) in Vietnamese tea samples by the infrared reflectance spectrophotometry coupled with chemometrics. The spectral range was 10,000-4,000cm-1 and each spectrum was measured at 2 cm-1 intervals. For the purpose of geographic origin classification, this study used FT-NIR spectroscopy combined with Partial Least Squares Discriminant Analysis (PLS-DA), and Principal Component Analysis-Discriminant Analysis (PCA-DA). The ability to determine the origin of tea samples in the prediction set of PLS-DA model is 100%. Using the same IR spectral database combined with the partial least squares (PLS), three methylxanthines in tea samples are also quickly quantified. The PLS model based on the spectra of 24 tea samples in which the contents of 3 analytes were determined by high performance liquid chromatography- HPLC) were applied for simultaneous determination of caffeine, theobromine and theophylline in samples. The determination of methylxanthines in 7 tea samples in test set gave the good accuracy of the PLS model. The correlation coefficients (R2) in the prediction set were of 0.9582, 0.8894 and 0.9303 for theobromine, theophylline, and caffeine, respectively. This work demonstrated that infrared reflectance spectrophotometry combined with chemometrics could be applied to rapidly classify the geographic origin and simultaneous determination of main contents in green tea.

The effects of exogenous substances on the color of heated bones.

Burned bone coloration has been used for decades to help in the bioanthropological analysis of burned human bones. However, there is a variety of factors that can interfere with the coloration manifested by bones exposed to heat, resulting in colors that differ from the usual black to white gradient. In this study, we evaluated possible causes of unusual coloration changes and hues in burned bone. For that purpose, defleshed fresh pig (Sus scrofa) ribs as well as fresh and dry human clavicles were burned at four different temperatures (500, 700, 900 and 1100°C) in contact with different materials (CaO, Zn, Fe, Cu, Mn, and polyester cloth). Observable color changes were assessed through naked eye observation and description, Munsell color charts, and reflectance spectrophotometry. Additionally, chemical changes in bone were assessed using Fourier-transform infrared spectroscopy in attenuated total reflectance (FTIR-ATR) and x-ray fluorescence (XRF). Our results showed that some materials did affect usual burned bone coloration (Fe, Mn, Cu, Zn) and correspondent FTIR-ATR and XRF spectra. As for other materials, although no effect on visual bone coloration was observed, they still affected FTIR-ATR and XRF spectra (CaO and cloth). This study can contribute to the anthropological analysis of burned human remains, providing some answers to what can cause unusual types of heat-induced colorations.

Integrated Ozonation Ni-NiO/Carbon/g-C3N4 Nanocomposite-Mediated Catalytic Decomposition of Organic Contaminants in Wastewater under Visible Light.

Developing a hybrid process for wastewater purification is of utmost importance to make conventional methods more efficient and faster. Herein, an effective visible light-active nickel-nickel oxide/carbon/graphitic carbon nitride (Ni-NiO/C/g-C3N4)-based nanocatalyst was developed. A hybrid process based on ozonation and Ni-NiO/C/g-C3N4 visible light photocatalysis was applied to decolourize the Congo red (CR), Alizarin Red S (ARS), and real dairy industry wastewater. The synthesized catalyst was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Χ-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectrophotometry (UV-Vis DRS). The factors affecting the catalytic process were evaluated, including contact time, solution pH, initial dye concentration, etc. The degradation rate of CR and ARS was compared between the photocatalysis, ozonation, and integrated photocatalytic ozonation (PC/O3) methods. The results showed 100% degradation of CR and ARS within 5 min and 40 min, respectively, by integrated PC/O3. The reusability of the modified catalyst was evaluated, and four successive regenerations were achieved. The modified Ni-NiO/C/g-C3N4 composite could be considered an effective, fast, and reusable catalyst in an integrated PC/O3 process for the complete decolourization of wastewater.

Plumage coloration differs between offspring raised in natural cavities and nestboxes

Abstract Most of our knowledge of secondary hole-nesting birds comes from populations breeding in human-provided nestboxes, yet these might differ from natural cavities in a number of parameters, including internal dimensions or microclimate, leading to differences in reproductive ecology. Here, we demonstrate differences in plumage coloration, an important visual signal of individual quality, in Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) nestlings raised in natural cavities and nestboxes. For this study, we collected feather samples over two breeding seasons and applied reflectance spectrophotometry to calculate color metrics. Carotenoid chroma was higher in nestbox-reared Blue Tits, whereas brightness was higher in nestbox-reared Great Tits (with a similar tendency for Blue Tits). The latter result might be explained by the better nutritional condition of Great Tit nestlings raised in nestboxes. Furthermore, we found no evidence for preference of adults expressing more elaborate plumage towards a specific cavity type in either species. Consequently, we assume that differences in nestling plumage reported here are driven by rearing conditions (nestboxes vs. natural cavities) and not by differences in plumage-based parental quality. Our study adds to the growing body of evidence confirming that anthropogenic environmental modifiers, such as nestboxes, might influence avian physiology and the resulting phenotype.

Effect of the β-tricalcium phosphate particle on dental enamel associated with 10% carbamide peroxide bleaching.

Since bleaching gels can cause adverse effects on tooth enamel, it is important to evaluate new remineralizing agents on the market and their effects. Seventy-five bovine enamel/dentin blocks (4x4x3mm) were randomly divided into six groups (n=10): Negative Control (NC) with no bleaching treatment or brushing; 10 CP (Carbamide Peroxide) (no brushing - Whiteness Perfect FGM); CT12 + 10 CP (Colgate Total® 12); ES + 10 CP (Elmex® Sensitive); BPC + 10 CP (Bianco® ProClinical); CMP + 10 CP (Colgate® Máxima Proteção Anticáries). The color was evaluated by reflectance spectrophotometry (∆E*ab, ∆E00, and ∆WID) at times T1 (baseline), T2 (24 hours after brushing), and T3 (24 hours after bleaching). Knoop microhardness (KHN) analysis were performed at T3. The enamel surface was qualitatively analyzed by Scanning Electron Microscopy (SEM). The data were analyzed using generalized linear models through descriptive and exploratory analyses, and a significance level of 5% was considered. Significant differences were observed when the bleached groups were compared to the NC group for ∆E*ab, ∆E00, and ∆WID at time T3 (p= <0.0001). However, the bleached groups presented no significant differences regarding studied times (p> 0.05). KHN did not differ significantly among the six groups (p=0.7585). Toothpastes with tricalcium phosphate (β-TCP) do not intervene with the efficacy of bleaching treatment with 10% carbamide peroxide. Although a slight mineral deposition on enamel surface can be observed on SEM images, KHN was not significantly altered, and the polishing of the samples were maintained. Key words:Dental Bleaching, Carbamide Peroxide, Hydrogen Peroxide, Dental Enamel, Tricalcium Phosphate.

Transition Temperature of Color Change in Thermochromic Systems and Its Description Using Sigmoidal Models

Background: Symmetric sigmoidal models with four parameters based on an idealized S/Z-shaped curve are commonly used to analyze the optical parameters of thermochromic materials. However, our experimental findings show that this approach leads to systematic errors involving the incorrect estimation of the transition temperature or the possibility of a virtual indication of the hysteresis nature of a reversible thermochromic change. For this reason, we sought to find a five-parameter model that would appropriately avoid this problem. Methods: Two commercial thermochromic pigments were used for the test and applied to a textile substrate at different concentrations. The optical properties were measured using reflectance spectrophotometry and then converted to Kubelka–Munk function values and colorimetric coordinates. The following statistics were used to assess the quality of the selected sigmoidal models: coefficient of determination, R2; adjusted coefficient of determination, AR2; root mean square error, RMSE; and Akaike Information Criterion, AIC. Results: The four-parameter models were compared with each other and with the five-parameter models using nested F-tests based on residual variance to obtain a statistical measure of superior performance. For all thermochromic color change data examined, the five-parameter models resulted in significantly better fitting. It could be shown that the five-parameter model showed significantly higher accuracy and precision in determining the transition temperature, like non-sigmoidal quantification methods. Conclusions: We concluded that the asymmetric five-parameter model is a valuable extension of the symmetric model in the investigation of thermochromic color changes, providing better parameter estimates and a new approach to investigating the mechanisms contributing to the asymmetry of the thermochromic curve.

The Surface Modification of Papers Using Laser Processing towards Applications.

This work presents the results of paper laser processing. It begins with the selection and examination of the processing parameters, then an examination of the properties of the modified papers and examples of applications of the developed modification method. The properties of laser-modified paper were studied using reflectance spectrophotometry to examine the colour aspects of the modified papers, scanning electron microscopy (SEM) and confocal microscopy for a morphological analysis, and Raman spectroscopy to analyse the papers under the influence of laser light. The influence of laser processing on the wettability of paper and the evenness of unprinted and printed paper was also investigated. The knowledge gained on paper surface modification with laser light was used to propose several applications, such as methods of marking, tactile detection, the controlled removal of optical brightener, ink, and metallised coatings from paper packaging, highlighting the design and aesthetics of paper. The developed laser-assisted method shows a promising, ecological approach to the design of many value-added paper products.

Textile Sublimation Printing: GLCM Print Mottle Assessment of Black Printed Fabric

The white fabric was printed with different printing temperatures and pressing times using the sublimation printing process in solid-tone black color with a 100 % total ink limiting level. Non-uniformity of the print was examined through print mottle determined by grey level co-occurrence matrix (GLCM) image processing method. Color strength of print was also determined by reflectance spectrophotometry. The print with the lower print mottle was obtained at a printing temperature of 190 °C at a longer pressing time of 120 s or at an increased printing temperature of up to 210 °C at the reduced pressing time of 60 s. The print with the lower print mottle had the lowest entropy, contrast, and correlation and the highest energy and homogeneity. The print with a higher color strength was accompanied by decreased print mottle. Choosing a suitable printing temperature and pressing time for sublimation printing is helpful in achieving print with low print mottle and high color strength and balancing cost, price, and price.

Correlation between Acanthosis Nigricans Scoring Chart (ANSC) and narrowband reflectance spectrophotometer in assessing severity of acanthosis nigricans.

There is a lack of standardized tool to monitor treatment outcome of acanthosis nigricans. To meet this end, we developed the Acanthosis Nigricans Scoring Chart (ANSC) that evaluates skin color (score range of 1-8) and skin texture (score range of 1-6), which adds up to a total ANSC score (score range of 2-14). We aimed to determine the correlation of ANSC to narrowband reflectance spectrophotometry and to evaluate its reliability. A cross-sectional study was conducted in adult acanthosis nigricans patients. Two raters independently graded participants using ANSC twice, in which scores were correlated to readings from Mexameter MX18. Intra- and interrater reliability were also evaluated via intraclass correlation coefficient (ICC). Participants had mean (sd) melanin and erythema indices of 615.8 (176.2) and 451.4 (53.4), respectively. Mean (sd) total ANSC score was 9.43 (2.43). The total ANSC score and skin color subdomain demonstrated strong correlations (r>0.6) with spectrophotometric results, whereas skin texture showed a moderate correlation (r=0.4-0.6). Total ANSC score generally had excellent intra- and interrater reliabilities (ICC>0.85). The total ANSC score and its subdomains strongly correlate with spectrophotometer and demonstrate excellent reliability in assessing acanthosis nigricans.

Optical and dielectric behaviors of polyvinyl chloride incorporated with MgFe2O4/MWCNTs

Casting and wet chemical methods have been used to produce polyvinyl chloride/magnesium ferrite/multi-walled carbon nanotubes (PVC-MgFe2O4-MWCNTs) polymer nanocomposites. Full characterization was carried out applying x-ray diffraction (XRD), scanning electron microscope (SEM/EDS), and Fourier transform infrared (FTIR) techniques. MWCNTs disclosed high crystalline nature and Rietveld refinement revealed nanostructure for MgFe2O4 with average size 16 nm. Optical properties were inferred by diffused reflectance spectrophotometry, fluorescence (FL), and chromaticity (CIE). Upon loading PVC with MgFe2O4/MWCNT, both direct and indirect bandgaps were reduced, the absorbance was enhanced greatly, while transmittance and reflectance were reduced. The refractive index was reduced except for PVC/MgFe2O4 where it enhanced for λ > 450 nm and increased with incident photon energy. The optical conductivity is highly enhanced for the whole wavelength range. According to FL and CIE results, the FL peak intensity of pure PVC polymer decreased upon loading MgFe2O4 and quenched further upon adding MWCNTs to the polymer. PVC emitted in the blue range while doped PVC emitted in blue-violet regions. The effect of MgFe2O4 and/or MWCNTs on the ac conductivity, electrical dielectric constant and electric modulus of PVC was investigated at room temperature. Based on the characterization data, the synthesized polymer nanocomposites have potential applications in several different optoelectronic settings.

PD03 Afamelanotide reduces the ultraviolet radiation erythemal response soon after application in healthy volunteers with skin phototypes II–III

Abstract Afamelanotide is a potent α-melanocyte stimulating hormone analogue that binds to the melanocortin 1 receptor and, over time, promotes tanning, conferring systemic photoprotection. Afamelanotide also has antioxidant properties and may promote repair of ultraviolet (UV) radiation (UVR)-induced DNA damage. The objectives of this study were to examine the short-term impact of afamelanotide on DNA damage repair mechanisms, UVR erythema and melanogenic responses in healthy human skin following exposure to UVR. Healthy men and women (n = 10) volunteers aged 27–43 years (median 34) of skin phototypes II–III were recruited. Reflectance spectrophotometry was performed on six body sites (photoexposed and photoprotected) to assess skin pigmentation, and then a geometric series of erythemally weighted doses (7–80 mJ cm−2) of broadband UVB (∼60% UVB, 40% UVA; Philips TL12) was applied to unexposed upper buttock skin. After 24 h, the minimal erythema dose (MED) was assessed and erythema intensity (CIE a*) was measured at each dose site. A subcutaneous implant of afamelanotide 16 mg was administered; 5 days later, the same UVR dose series was applied to unexposed contralateral upper buttock skin. After 24 h, the MED was assessed and repeat skin reflectance measurements were performed. The overall UVR–erythema dose response (area under curve) showed a significant decrease post-afamelanotide (mean 3.5 vs. 2.7; P = 0.018). There was an apparent increase in the median MED post-afamelanotide (24.5 vs. 29.9 mJ cm−2; not statistically significant). Reflectance measurements showed skin lightness (CIE L*) significantly decreased at only one site (central forehead, from 63.0 to 61.0; P = 0.015), while determination of melanin density by reflectance at 420 and 400 nm showed a statistically significant increase in density at all sites except the right abdomen, with a mean overall increase from 2.5% to 2.9% (P = 0.001). Our results indicate that afamelanotide reduces the overall UVR–erythema dose response in healthy human skin shortly after administration, with a small increase in melanogenesis, suggesting other nonmelanogenic properties of this agent contribute to the erythema protection. Further investigation will examine whether enhanced repair of UVR-induced DNA damage plays a role. Funding sources: research sponsored by CLINUVEL (UK) Ltd.

Synthesis and photocatalytic effects of TiO2-Ag on antibiotic-resistant bacteria

Titanium dioxide (TiO2) is a semiconductor metal oxide extensively studied due to its photocatalytic properties that can be applied in various areas. However, the catalytic performance of TiO2 is limited at the UV spectrum, and the silver doping to titanium dioxide (Ag-TiO2) can increase the catalytic performance for visible light. In this work, Ag-doped TiO2 nanoparticles were synthesized to evaluate photocatalytic activity against sensitive and methicillin-resistant Staphylococcus aureus frequently associated with skin infections. The sol-gel method followed by Ag doping was applied to NPs synthesis. NPs were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM), UV-vis diffuse reflectance spectrophotometry (DRS), Semi-quantitative energy dispersive spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy. FTIR and EDS results confirmed the doping of silver in TiO2. MEV analysis evidenced spherical nanoparticles between 8.5 - 25.6 nm. The TiO2 nanoparticles combined with silver improved the antimicrobial effect of TiO2 under visible light at 180 min, however, the greatest antimicrobial effect was observed under UV light at 120 min.

Seasonal Tanning-Induced Increases in Skin Pigmentation Do Not Affect Nitric Oxide-Mediated Vasodilation of the Cutaneous Microvasculature

Acute ultraviolet radiation (UVR) exposure reduces nitric oxide (NO)-dependent cutaneous vasodilation. Additionally, increased constitutive skin melanin concentrations are associated with reduced NO-dependent cutaneous vasodilation. However, the impact of seasonal tanning-induced increases in skin melanin concentration on NO-dependent cutaneous vasodilation has not been investigated. PURPOSE: To investigate the effect of seasonal tanning-induced increases in skin melanin on the NO-dependent cutaneous vasodilation response to local heating. We hypothesized that NO-dependent cutaneous vasodilation would be reduced in tanned skin relative to untanned skin. METHODS: Three intradermal microdialysis fibers were placed in the ventral upper arm (least sun exposed), ventral forearm (moderately sun exposed), and dorsal forearm (most sun exposed) of seven adults (33 ± 14 yrs; 4M/3F) with light-to-moderate constitutive skin pigmentation. Differences in sun exposure among the sites was confirmed using the melanin-index (M-index; an index of skin pigmentation), measured via skin reflectance spectrophotometry. Lactated Ringer’s solution was perfused through the microdialysis fibers while local heating to 42°C induced cutaneous vasodilation. After attaining a stable plateau in cutaneous blood flow, 15mM NG-nitro-L-arginine methyl ester (L-NAME; NO synthase inhibitor) was perfused at all sites to quantify NO-mediated vasodilation. Red cell flux was measured using laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC=LDF/mean arterial pressure) was calculated for each phase of the local heating response (i.e., baseline, initial peak, local heating plateau, post L-NAME plateau) and expressed as percent maximum (%CVCmax; 28mM sodium nitroprusside + 43°C local heating). RESULTS: M-index was highest (i.e., skin pigmentation was darkest) in the dorsal forearm (50.5 ± 11.8 a.u.) compared to the ventral forearm (37.5 ± 7.4 a.u.; p ≤ 0.03) and upper arm (30.2 ± 5.1 a.u.; p ≤ 0.001). There were no baseline (p ≥ 0.37), initial peak (p ≥ 0.22), post L-NAME plateau (p ≥ 0.12), or maximal CVC (p ≥ 0.23) differences among the three sites. Likewise, the magnitude of the local heating plateau was not different among the three sites (dorsal: 88±17%; ventral: 81±20%; upper: 90±12%; p ≥ 0.16), nor was NO-mediated vasodilation (dorsal: 59±15%; ventral: 54±13%; upper: 55±11.0%; p ≥ 0.79). CONCLUSION: These data suggest that, in contrast to the effects of acute UVR exposure or a constitutively dark skin pigmentation, seasonal tanning-induced increases in skin pigmentation do not alter NO-dependent cutaneous vasodilation responses to local heating. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparative study of Brazilian Military Police Uniforms

Although there are literature studies on military uniforms, few investigate those used by the Military Police (MP). As such, the present study aimed to characterize the structural, colorimetric and mechanical properties of Brazilian MP Uniforms. To that end, yarn count, fabric weight, yarn density, weave pattern, optical microscopy, fastness, reflectance spectrophotometry and tensile strength tests were performed on uniforms from MPMG, MPSC and MPRN (Military Police from the states of Minas Gerais, Santa Catarina and Rio Grande do Norte, respectively). Structural similarities between the MPMG and MPSC uniforms were detected, and significant differences in relation to the MPRN. The three uniforms displayed satisfactory performance in dry rubbing fastness, and unsatisfactory in wet rubbing fastness and loss of color after washing. Thus, there is significant room for improvement in military police uniforms in Brazil.

Near-ultraviolet absorption distribution of primitive asteroids from spectrophotometric surveys

Context. Hydrated minerals, such as phyllosilicates, on asteroids can provide constraints on the temperature or compositional distribution of the early Solar System. Previous studies pointed out the possibility that absorption in the near-ultraviolet (NUV, 0.35–0.5 μm) wavelength region is a proxy for hydrated minerals in primitive asteroids. However, the radial distribution of the NUV absorption among primitive asteroids was not revisited after the Eight Color Asteroid Survey (ECAS). Aims. Our objectives are first to evaluate the possibility of using the NUV absorption as diagnostics of hydrated minerals based on the recent datasets of primitive asteroids and hydrated carbonaceous chondrites, and second to investigate the reflectance spectrophotometry of the primitive asteroids in the NUV as functions of heliocentric distance and size. Methods. The NUV and visible reflectance spectrophotometry of more than 9000 primitive asteroids was investigated using two spectrophotometric surveys, ECAS and the Sloan Digital Sky Survey (SDSS), which cover wavelengths down to 0.32 μm and 0.36 μm, respectively. We classified asteroids from the main asteroid belt, the Cybele and Hilda zones, and Jupiter Trojans based on Tholen’s taxonomy and described the statistical distribution of primitive asteroid types. We also examined the relationship of the NUV, 0.7 μm, and 2.7 μm absorptions among primitive asteroids and hydrous carbonaceous chondrites CI and CM. Results. We find strong correlations between the NUV and the OH-band (2.7 μm) absorptions for primitive asteroids and hydrated meteorites, suggesting the NUV absorption can be indicative of hydrated silicates. Moreover, there is a great difference in the NUV absorption between the large asteroids (diameter d &gt; 50 km) and small asteroids (d &lt; 10 km) in the taxonomic distribution. The taxonomic distribution of asteroids differs between the inner main belt and middle-outer main belt. Notably, the C types are dominating large members through the main belt and the F types are dominating small asteroids of the inner main belt. The asteroids beyond the main belt consist mostly of P and D types, although P types are common everywhere in the main belt. The peculiar distribution of F types might indicate a different formation reservoir or a displacement process of F types in the early Solar System. The strongest absorptions of the NUV and 0.7 μm band were observed in G types, which likely comprise CM-like Fe-rich phyllosilicates. On the other hand, according to a recent sample return from an F-type asteroid (162173) Ryugu, the F types with the OH-band at 2.7 μm and the shallow NUV absorption could comprise CI-like Mg-rich phyllosilicates.

Wide-gamut structural colours on oakblue butterflies by naturally tuned photonic nanoarchitectures.

The iridescent structural colours of butterflies, generated by photonic nanoarchitectures, often function as species-specific sexual signals; therefore, they are reproduced precisely from generation to generation. The wing scales of oakblue hairstreak butterflies (genus Arhopala, Theclinae, Lycaenidae, Lepidoptera) contain multi-layer photonic nanoarchitectures, which can generate a wide range of structural colours, from violet to green. By scanning (SEM) and cross-sectional transmission electron microscopy (TEM) investigation, the colour tuning mechanism of the cover scales was explored. We revealed that the characteristic size change of structural elements in similar photonic nanoarchitectures led to different structural colours that were examined by various reflectance spectrophotometry techniques. The measured structural properties of the naturally tuned photonic nanoarchitectures were used to calculate wing reflectances, which were compared with the measurement results. We found that the simulated structural colours were systematically redshifted by 95-126 nm as compared with the measured normal-incidence reflectance results. This is attributed to the swelling of the chitinous multi-layer structures during the standard TEM sample preparation and the tilt of the cover scales, which both affect the apparent layer thicknesses in the TEM cross-sections. We proposed a simulation correction and compared the results with the layer thicknesses measured on cryogenically prepared non-embedded SEM cross-sections.

A hypothesis for robust polarization vision: an example from the Australian imperial blue butterfly, Jalmenus evagoras.

The Australian lycaenid butterfly Jalmenus evagoras has iridescent wings that are sexually dimorphic, spectrally and in their degree of polarization, suggesting that these properties are likely to be important in mate recognition. We first describe the results of a field experiment showing that free-flying individuals of J. evagoras discriminate between visual stimuli that vary in polarization content in blue wavelengths but not in others. We then present detailed reflectance spectrophotometry measurements of the polarization content of male and female wings, showing that female wings exhibit blue-shifted reflectance, with a lower degree of polarization relative to male wings. Finally, we describe a novel method for measuring alignment of ommatidial arrays: by measuring variation of depolarized eyeshine intensity from patches of ommatidia as a function of eye rotation, we show that (a) individual rhabdoms contain mutually perpendicular microvilli; (b) many rhabdoms in the array have their microvilli misaligned with respect to neighboring rhabdoms by as much as 45deg; and (c) the misaligned ommatidia are useful for robust polarization detection. By mapping the distribution of the ommatidial misalignments in eye patches of J. evagoras, we show that males and females exhibit differences in the extent to which ommatidia are aligned. Both the number of misaligned ommatidia suitable for robust polarization detection and the number of aligned ommatidia suitable for edge detection vary with respect to both sex and eye patch elevation. Thus, J. evagoras exhibits finely tuned ommatidial arrays suitable for perception of polarized signals, likely to match sex-specific life history differences in the utility of polarized signals.

Oxygen saturation in intraosseous sternal blood measured by CO-oximetry and evaluated non-invasively during hypovolaemia and hypoxia – a porcine experimental study

Purpose: This study intended to determine, and non-invasively evaluate, sternal intraosseous oxygen saturation (SsO2) and study its variation during provoked hypoxia or hypovolaemia. Furthermore, the relation between SsO2 and arterial (SaO2) or mixed venous oxygen saturation (SvO2) was investigated. Methods: Sixteen anaesthetised male pigs underwent exsanguination to a mean arterial pressure of 50 mmHg. After resuscitation and stabilisation, hypoxia was induced with hypoxic gas mixtures (air/N2). Repeated blood samples from sternal intraosseous cannulation were compared to arterial and pulmonary artery blood samples. Reflection spectrophotometry measurements by a non-invasive sternal probe were performed continuously. Results: At baseline SaO2 was 97.0% (IQR 0.2), SsO2 73.2% (IQR 19.6) and SvO2 52.3% (IQR 12.4). During hypovolaemia, SsO2 and SvO2 decreased to 58.9% (IQR 16.9) and 38.1% (IQR 12.5), respectively, p < 0.05 for both, whereas SaO2 remained unaltered (p = 0.44). During hypoxia all saturations decreased; SaO2 71.5% (IQR 5.2), SsO2 39.0% (IQR 6.9) and SvO2 22.6% (IQR 11.4) (p < 0.01), respectively. For hypovolaemia, the sternal probe red/infrared absorption ratio (SQV) increased significantly from baseline (indicating a reduction in oxygen saturation) + 5.1% (IQR 7.4), p < 0.001 and for hypoxia + 19.9% (IQR 14.8), p = 0.001, respectively. Conclusion: Sternal blood has an oxygen saturation suggesting a mixture of venous and arterial blood. Changes in SsO2 relate well with changes in SvO2 during hypovolaemia or hypoxia. Further studies on the feasibility of using non-invasive measurement of changes in SsO2 to estimate changes in SvO2 are warranted.

Jute fabric in the development of a smart thermochromic textile

In recent years, the market has shown a growing interest in adding value to textile materials through the search for natural processes that are less harmful to the environment. In this context, the use of natural fibers from plants provides very attractive properties, such as biodegradability, UV protection, acoustic insulation, among others. In this way, the purpose of this work was to functionalize a fabric from jute fiber with a thermochromic agent, making it a material with an intelligent property, being able to react thermally to the environment in which it is inserted. Through the analysis of reflectance spectrophotometry, the L*, a* and b* coordinates of the targeted and functionalized tissues were observed. When the ?E of the samples functionalized at 4 different points was analyzed, good homogeneity of the thermochromic agent in the tissue was verified. The aging effect of the thermochromic agent was evaluated on the tissue for 1, 15 and 30 days after functionalization, where a slight increase in the b* value was observed, which indicates a certain loss of blue coloration in the sample. It was verified, therefore, that the functionalized jute fabric presented satisfactory results, allowing its use in other areas of application, mainly when referring to the interaction with the environment in which it is inserted.